Image sensor device and fabricating method thereof

ABSTRACT

An image sensor device includes a substrate, a photo sensitive element, a first dielectric structure and a convex dielectric lens. The substrate has a first side and a second side opposite to the first side. The photo sensitive element is formed on the first side of the substrate for receiving incident light transmitted through the substrate. The first dielectric structure is formed on the second side of the substrate. At least one portion of the convex dielectric lens is located in the first dielectric structure. The convex dielectric lens has a convex side oriented toward the incident light and a planar side oriented toward the photo sensitive element.

BACKGROUND

Image sensor devices are widely used in various imaging applications andproducts, such as smart phones, digital cameras, scanners, etc.Typically, an image sensor device uses micro-lenses to condense incidentlight into color filters when the incident light first enters the imagesensor device. However, various dielectric films used in the imagesensor device with CMOS technology increase the number of optical paths,and such films are transparent to visible light. Even if the imagesensor device includes a grid to block the optical paths from crossingsubpixels, the incident light may dissipate (e.g. penetrate into otherpixels under the grid), in which a crosstalk issue arises, resulting insignal-to-noise ratio (SNR) degradation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the followingdetailed description of the embodiment, with reference made to theaccompanying drawings as follows:

FIG. 1 illustrates a schematic cross-sectional diagram of an imagesensor device in accordance with some embodiments of the presentdisclosure;

FIGS. 2A-2B illustrate schematic enlarged partial views of the imagesensor device in FIG. 1 in accordance with various embodiments;

FIGS. 3A-3H illustrate schematic cross-sectional diagrams ofintermediate stages in accordance with a method for fabricating an imagesensor device in some embodiments of the present disclosure; and

FIG. 4 illustrates a flow chart of a method for fabricating an imagesensor device in accordance with some embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The making and using of the present embodiments are discussed in detailbelow. It should be appreciated, however, that the present disclosureprovides many applicable concepts that can be embodied in a wide varietyof specific contexts. The specific embodiments discussed are merelyillustrative of specific ways to make and use the disclosed subjectmatter, and do not limit the scope of the different embodiments.

Terms used herein are only used to describe the specific embodiments,which are not used to limit the claims appended herewith. For example,unless limited otherwise, the term “one” or “the” of the single form mayalso represent the plural form. The terms such as “first” and “second”are used for describing various devices, areas and layers, etc., thoughsuch terms are only used for distinguishing one device, one area or onelayer from another device, another area or another layer. Therefore, thefirst area can also be referred to as the second area without departingfrom the spirit of the claimed subject matter, and the others arededuced by analogy. Moreover, space orientation terms such as “under”,“on”, “up”, “down”, etc. are used to describe a relationship between adevice or a characteristic and another device or another characteristicin the drawing. It should be noted that the space orientation term cancover different orientations of the device besides the orientation ofthe device illustrated in the drawing. For example, if the device in thedrawing is turned over, the device located “under” or “below” the otherdevices or characteristics is reoriented to be located “on” or “above”the other devices or characteristics. Therefore, the space orientationterm “on” may include two orientations of “above” and “below”.

Embodiments of the present disclosure are directed to providing an imagesensor device for better photo sensing quality. In each pixel region ofthe image sensor device, a convex dielectric lens is formed between acolor filter and a substrate for condensing incident light into a photosensitive element, such that quantum efficiency is improved and acrosstalk issue is avoided for high signal-to-noise (SNR) ratio, therebyimproving the photo sensing quality.

Referring to FIG. 1, FIG. 1 illustrates a schematic cross-sectionaldiagram of an image sensor device 100 in accordance with someembodiments of the present disclosure. In the present disclosure, theimage sensor device 100 is a backside illuminated (BSI) image sensordevice. The image sensor device 100 includes pixel regions 100R, 1000and 100B for converting incident light into RGB image data. It is notedthat the sequence of the pixel regions 100R, 1000 and 100B shown in FIG.1 is shown as an example for explanation, and embodiments of the presetdisclosure are not limited thereto.

In FIG. 1, the image sensor device 100 includes a substrate 110, photosensitive elements 120R/120G/120B, pixel circuits 122R/122G/122B, afirst dielectric structure 130, convex dielectric lenses 140, a grid150, a second dielectric structure 160, color filters 170R/170G/170B andmicro-lenses 180. The substrate 110 is a semiconductor substrate, whichincludes, but not limited to, a semiconductor wafer, asilicon-on-insulator (SOI) substrate, an epitaxial substrate. In someembodiments, the substrate 110 further includes an elementarysemiconductor such as silicon, germanium and diamond. In anotherembodiments, the substrate 100 further includes a compoundsemiconductor, such as silicon carbide, gallium arsenic, galliumcarbide, gallium phosphide, indium arsenide and indium phosphide, or analloy semiconductor, such as silicon germanium, silicon germaniumcarbide, gallium arsenic phosphide and gallium indium phosphide.

The substrate 110 has a front side 110A and a back side 110B. The photosensitive elements 120R/120G/120B are formed on the front side 110A ofthe substrate 110. The photo sensitive elements 120R/120G/120B areconfigured to receive the incident light transmitted from the back side110B through the substrate 110, and then to convert the incident lightto RGB image data. In some embodiments, the photo sensitive element120R/120G/120B are photodiodes, pinned photodiodes, partially pinnedphotodiodes, photogates or photo transistors.

The pixel circuits 122R/122G/122B are formed on the front side 110A ofthe substrate 110 and adjacent the photo sensitive elements120R/120G/120B respectively for electrical interconnecting with thephoto sensitive elements 120R/120G/120B, so as to transfer electriccharges generated from the photo sensitive elements 120R/120G/120B. Forillustration, each of the pixel circuits 122R/122G/122B includes a resettransistor, a source follower transfer, a row select transistor and atransfer transistor.

The first dielectric structure 130 is formed on the back side 110B ofthe substrate 110. In FIG. 1, the first dielectric structure 130includes a first dielectric layer 132 and a second dielectric layer 134.The first dielectric layer 132 is formed on the back side 110B of thesubstrate 110, and the second dielectric layer 134 is formed on thefirst dielectric layer 132. The first dielectric layer 132 and thesecond dielectric layer 134 may include a transparent material, such assilicon oxide, silicon nitride, combinations thereof, or the like. Insome embodiments, that the material forming the first dielectric layer132 is selected to have a refractive index greater than that of thesecond dielectric layer 134.

In each of the pixel regions 100R/100G/100B, the convex dielectric lens140 is formed in the first dielectric structure 130. As shown in FIG. 1,the second dielectric layer 134 includes recesses for forming the convexdielectric lenses 140 therein. At least one portion of each of theconvex dielectric lenses 140 is located in the second dielectric layer134. In other words, a height of each of the convex dielectric lenses140 may be greater than, equal to or smaller than a depth of each of therecesses. Each of the convex dielectric lenses 140 has a refractiveindex lower than that of the second dielectric layer 134. Each of theconvex dielectric lenses 140 has a convex side 140A and a planar side140B. The convex side 140A is oriented toward the incident light,whereas the planar side 140B is directly on the recess 136 and orientedtoward the photo sensitive element 120R/120G/120B.

In some embodiments, the first dielectric structure 130 is a singlelayer structure. The first dielectric structure 130 may include atransparent material, such as silicon oxide, silicon nitride,combinations thereof, or the like. The first dielectric structure 130has a refractive index greater than that of each of the convexdielectric lenses 140.

The grid 150 is formed on the first dielectric structure 130. The grid150 separates the pixel regions 100R/100G/100B for preventing theincident light from passing therethrough. In some embodiments, the grid150 includes an insulating material such as silicon oxide, siliconnitride, silicon oxynitride, combinations thereof, or the like. In someembodiments, the grid 150 includes a metal material such as aluminum,copper, or the like, a metal alloy material such as aluminum alloy,copper alloy, or the like, a metal nitride such as titanium nitride,tantalum nitride, or other suitable material.

The second dielectric structure 160 is formed on the first dielectricstructure 130, the convex dielectric lenses 140 and the grid 150. Thesecond dielectric layer 160 may include a transparent material, such assilicon oxide, silicon nitride, combinations thereof, or the like. Thematerial of the second dielectric structure 160 is selected to have arefractive index smaller than that of each of the convex dielectriclenses 140. In some embodiments, the second dielectric structure 160 atleast partially covers the convex dielectric lenses 140.

The color filters 170R/170G/170B are formed on the second dielectricstructure 160 and respectively in the pixel regions 100R/100G/100B. Thecolor filters 170R/170G/170B filter the incident light to thereby obtainred, green and blue lights, respectively. For illustration, the colorfilters 170R/170G/170B include a dyed or pigmented material such aspolymer, or other suitable material.

The micro-lenses 180 are formed on the color filters 170R/170G/170B andin the pixel regions 100R/100G/100B respectively. The micro-lenses 180focus the incident light onto the photo sensitive elements120R/120G/120B. For illustration, the micro-lenses 180 are formed of anymaterial that may be patterned and formed into lenses with hightransmittance, such as acrylic polymer and other suitable material.

Referring to FIGS. 2A-2B, FIGS. 2A-2B illustrate enlarged partial viewsof the image sensor device 100 shown in FIG. 1 in accordance withvarious embodiments. Each of the convex dielectric lenses 140 has awidth W and a height H. As shown in FIG. 2A, the width W of the convexdielectric lens 140 is substantially identical to a distance D betweentwo opposite sides of the grid 150, and the height H of the convexdielectric lens 140 is substantially identical to a thickness T of thesecond dielectric layer 134. Alternatively, the height H of the convexdielectric lens 140 may be smaller than the thickness T of the seconddielectric layer 134. In such cases, the convex dielectric lens 140 isentirely in the second dielectric layer 134. In some embodiments, asshown in FIG. 2B, the height H of the convex dielectric lens 140 isgreater than the thickness T, such that a portion 142 of the convexdielectric lens 140 is in the second dielectric layer 134. The height Hof the convex dielectric lens 140 may vary in accordance with therefractive indexes of the convex dielectric lens 140, the firstdielectric layer 132 and the second dielectric structure 160. Further,in certain embodiments, the width W of the convex dielectric lens 140may be greater than the distance D.

Referring to FIGS. 3A-3H, FIGS. 3A-3H illustrate cross-sectionaldiagrams for fabricating an image sensor device 300 in accordance withsome embodiments of the present disclosure. In FIG. 3A, a substrate 310,photo sensitive elements 320R/320G/320B and pixel circuits322R/322G/322B are provided. The substrate 310 is a semiconductorsubstrate, which includes, but not limited to, a semiconductor wafer, asilicon-on-insulator (SOI) substrate or an epitaxial substrate. In someembodiments, the substrate 310 further includes an elementarysemiconductor, a compound semiconductor or an alloy semiconductor. Thephoto sensitive elements 320R/320G/320B are formed on the front side310A of the substrate 310 and in the pixel regions 300R/300G/300Brespectively. In some embodiments, the photo sensitive elements320R/320G/320B are formed by a diffusion process or an ion implantationprocess. For illustration, if the photo sensitive elements320R/320G/320B are PNP-type photodiodes formed by the ion implantationprocess, the photo sensitive elements 320R/320G/320B includes P-typepinned layers formed on N-type doped regions, and the substrate 310 is aP-type semiconductor substrate, in which the N-type doped regions areformed on the substrate 310. In addition, the pixel circuits322R/322G/322B are formed on the front side 310A of the substrate 310and adjacent the photo sensitive elements 320R/320G/320B respectively.

In FIG. 3B, a first dielectric layer 332 is formed on the back side 310Bof the substrate 310 opposite to the front site 310A. For illustration,the first dielectric layer 332 is formed by a deposition process such aschemical vapor deposition (CVD), physical vapor deposition (PVD), atomiclayer deposition (ALD), combinations thereof, or the like.

In FIG. 3C, a second dielectric layer 334 is formed on the firstdielectric layer 332. For illustration, the second dielectric layer 334is formed by a deposition process such as CVD, PVD, ALD, combinationsthereof, or the like. The first dielectric layer 332 and the seconddielectric layer 334 forms a first dielectric structure 330. In someembodiments, the material of the first dielectric layer 332 and thesecond dielectric layer 334 are selected, such that the first dielectriclayer 332 has a refractive index greater than the second dielectriclayer 334.

In FIG. 3D, an isolating layer 340 is formed on the second dielectriclayer 334. In some embodiments, the isolating layer 340 includes aninsulating material such as silicon oxide, silicon nitride, siliconoxynitride, combinations thereof, or the like. In some embodiments, theisolating layer 340 includes a metal material such as aluminum, copper,or the like, a metal alloy material such as aluminum alloy, copperalloy, or the like, a metal nitride such as titanium nitride, tantalumnitride, or other suitable material. For illustration, the isolatinglayer 340 is formed by a deposition process such as CVD, PVD, or anysuitable process.

In FIG. 3E, a grid 342 and recesses 344R/344G/344B are formed by anetching process. The recesses 344R/344G/344B are formed by removingparts of the isolating layer 340 and the second dielectric layer 334.For illustration, the etching process includes dry etching, wet etching,drilling, combinations thereof, or the like. Bottoms of the recesses344R/344G/344G directly adjoin the first dielectric layer 332. The grid342 is also formed for separating the pixel regions 300R/300G/300B afterthe etching process is done.

In FIG. 3F, convex dielectric lenses 350 are formed in the recesses344R/344G/344B and directly on the first dielectric layer 332. Theconvex dielectric lenses 350 are formed by a deposition process such asCVD, PVD, or the like. In each of the pixel regions 300R/300G/300B, theconvex dielectric lens 350 is formed to have a convex side 350A orientedopposite to one of the photo sensitive elements 320R/320G/320B and aplanar side 350B oriented toward one of the photo sensitive elements320R/320G/320B. The material of the convex dielectric lenses 350 isselected to have a refractive index smaller than that of the firstdielectric layer 332. In some embodiments, the refractive index of eachof the convex dielectric lenses 350 is smaller than the seconddielectric layer 334.

In the pixel regions 300R/300G/300B, the width and height of the convexdielectric lenses 350, the thickness of the second dielectric layer 334and the width of the recesses 344R/344G/344G (i.e. the distance betweentwo opposite sides of the grid 342) are adjustable in accordance withvarious embodiments. In some embodiments, the width of each of theconvex dielectric lenses 350 is substantially equal to or greater thanthe width of each of the recesses 344R/344G/344G. In some embodiments,the height of each of the convex dielectric lenses 350 is substantiallyequal to or greater than the thickness of the second dielectric layer334.

In FIG. 3G, a second dielectric structure 360 is formed on the firstdielectric structure 330, the convex dielectric lenses 350 and the grid342. The second dielectric structure 360 is formed to fill in therecesses 344R/344G/344B. For illustration, the second dielectricstructure 360 is formed by a deposition process such as CVD, PVD, ALD,combinations thereof, or the like. The material of the second dielectricstructure 360 is selected to have a refractive index smaller than thatof each of the convex dielectric lenses 350. In some embodiments, thesecond dielectric structure 360 at least partially covers the convexdielectric lenses 350.

In FIG. 3H, color filters 370R/370G/370B are formed on the seconddielectric structure 360. For illustration, the color filters370R/370G/370B are selectively patterned and sequentially formed by anexposure and development process using a photo-mask.

Further, in FIG. 3H, micro-lenses 380 are respectively formed on thecolor filters 370R/370G/370B. For illustration, the micro-lenses 380 areformed using a material in a liquid state by a spin-on technique. Suchmethod is performed to produce a substantially planar surface andmicro-lenses 380 with a substantially uniform thickness. In someembodiments, other methods, such as CVD, PVD, and/or the like, are alsoperformed for forming the micro-lenses 380.

Referring to FIG. 4 with FIGS. 3A-3H, FIG. 4 is a flow chart of a method400 for fabricating an image sensor device in accordance with someembodiments. The method 400 begins at operation 402, where a substrate310 is provided, as shown in FIG. 3A. At operation 404, a photosensitive element 320R/320G/320B is formed on a front side 310A of thesubstrate 310 for receiving incident light transmitted through thesubstrate 310. At operation 406, a pixel circuit 322R/322G/322B isformed on the front side 310A of the substrate 310 for electricalinterconnection with the photo sensitive element 320R/320G/320B. Atoperation 408, a first dielectric structure 330 is formed on the backside 310B of the substrate 310. In some embodiments, the firstdielectric structure 330 includes a first dielectric layer 332 formed onthe back side 310B and a second dielectric layer 334 formed on the firstdielectric layer 332, as shown in FIGS. 3B-3C. At operation 410, aninsulating layer 340 is formed on the first dielectric structure 330, asshown in FIG. 3D. At operation 412, a grid 342 and a recess344R/344G/344B are formed by performing an etching process to removeparts of the isolating layer 340 and a portion of the first dielectricstructure 330, as shown in FIG. 3E. At operation 414, a convexdielectric lens 350 is formed in the recess 344R/344G/344B, as shown inFIG. 3F. At operation 416, a second dielectric structure 360 is formedon the first dielectric structure 330, the convex dielectric lens 350and the grid 344, as shown in FIG. 3G. At operation 418, a color filter370R/370G/370B is formed on the second dielectric structure 360, and amicro-lens 380 is formed on the color filter 370R/370G/370B, as shown inFIG. 3H.

In accordance with the embodiments of the present disclosure, anadditional convex dielectric lens is formed between a color filter and asubstrate in each pixel region of an image sensor device, and the convexdielectric lens has a refractive index greater than that of a dielectricstructure on a convex side of the convex dielectric lens. Thus, incidentlight is condensed into a photo sensitive element in a more effectivemanner, such that the quantum efficiency of the image sensor device isimproved. In addition, since the crosstalk issue is avoided, the SNR ofthe image sensor device increases.

It is noted that, the aforementioned convex dielectric lenses in thepresent disclosure may be replaced with concave dielectric lenses inaccordance with various embodiments. For example, a concave dielectriclens may be formed in replace of the aforementioned convex dielectriclens in each pixel region to have a planar side oriented toward incidentlight and a concave side oriented toward the photo sensitive element,and the concave dielectric lens has a refractive index greater than thatof the aforementioned second dielectric structure and smaller than thatof the aforementioned first dielectric layer. Further, in someembodiments, the first dielectric structure is a single layer structure,and the convex dielectric lenses directly adjoin the back side of thesubstrate.

In accordance with some embodiments, the present disclosure discloses animage sensor device. The image sensor device includes a substrate, aphoto sensitive element, a first dielectric structure and a convexdielectric lens. The substrate has a first side and a second sideopposite to the first side. The photo sensitive element is formed on thefirst side of the substrate for receiving incident light transmittedthrough the substrate. The first dielectric structure is formed on thesecond side of the substrate. At least one portion of the convexdielectric lens is located in the first dielectric structure. The convexdielectric lens has a convex side oriented toward the incident light anda planar side oriented toward the photo sensitive element.

In accordance with another embodiment, the present disclosure disclosesan image sensor device. The image sensor device includes a substrate, aphoto sensitive element, a first dielectric layer, a second dielectriclayer and a convex dielectric lens. The substrate has a first side and asecond side opposite to the first side. The photo sensitive element isformed on the first side of the substrate for receiving incident lighttransmitted through the substrate. The first dielectric layer is formedon the second side of the substrate. The second dielectric layer isdirectly on the first dielectric layer and has a recess therein. Theconvex dielectric lens is formed on the first dielectric layer. At leastone portion of the convex dielectric lens is located in the recess. Theconvex dielectric lens has a convex side oriented toward the incidentlight and a planar side oriented toward the photo sensitive element.

In accordance with yet another embodiment the present disclosurediscloses a method of fabricating an image sensor device. The methodincludes providing a substrate having a first side and a second sideopposite to the first side; forming a photo sensitive element on thefirst side of the substrate for receiving incident light transmittedthrough the substrate; forming a first dielectric structure on thesecond side of the substrate; forming a recess by removing a portion ofthe first dielectric structure; and forming a convex dielectric lens inthe recess of the first dielectric structure, the convex dielectric lenshaving a convex side oriented toward the incident light and a planarside oriented toward the photo sensitive element.

Although the present embodiments and their advantages have beendescribed in detail, it should be understood that various changes,substitutions and alterations can be made herein without departing fromthe spirit and scope of the disclosure as defined by the appendedclaims.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A backside illuminated (BSI) image sensor device,comprising: a substrate having a first side and a second side oppositeto the first side; a photo sensitive element on the first side of thesubstrate to receive incident light transmitted through the substrate; apixel circuit on the first side of the substrate for electricalinterconnecting with the photo sensitive element; a first dielectriclayer disposed on the second side of the substrate; a second dielectriclayer directly on the first dielectric layer, wherein a refractive indexof the first dielectric layer is greater than a refractive index of thesecond dielectric layer; a grid on the second dielectric layer, whereina sidewall of the grid is coplanar with a sidewall of the seconddielectric layer; and a convex dielectric lens on the first dielectriclayer and provided within the second dielectric layer, the convexdielectric lens having a convex side oriented toward the incident lightand a planar side oriented toward the photo sensitive element, wherein abottom of the convex side of the convex dielectric lens is level with abottom surface of the second dielectric layer and a refractive index ofthe convex dielectric lens is smaller than the refractive index of thesecond dielectric layer.
 2. The BSI image sensor device of claim 1,further comprising: a dielectric structure on the second dielectriclayer, the convex dielectric lens and the grid, the dielectric structureat least partially covering the convex dielectric lens.
 3. The BSI imagesensor device of claim 2, wherein a refractive index of the convexdielectric lens is greater than a refractive index of the dielectricstructure.
 4. The BSI image sensor device of claim 2, furthercomprising: a color filter on the dielectric structure; and a micro-lenson the color filter.
 5. The BSI image sensor device of claim 1, whereinthe convex dielectric lens is sandwiched by opposite sides of the seconddielectric layer and the grid.
 6. The BSI image sensor device of claim4, wherein the convex dielectric lens is aligned with the micro-lens. 7.A method of fabricating a backside illuminated (BSI) image sensordevice, the method comprising: providing a substrate having a first sideand a second side opposite to the first side; forming a photo sensitiveelement on the first side of the substrate for receiving incident lighttransmitted through the substrate; forming a first dielectric layer onthe second side of the substrate; forming a second dielectric layerdirectly on the first dielectric layer, wherein a refractive index ofthe first dielectric layer is greater than a refractive index of thesecond dielectric layer; forming a metal layer on the second dielectriclayer; etching the metal layer and the second dielectric layer to form agrid on the second dielectric layer and a recess in the seconddielectric layer; and forming a convex dielectric lens in the recess,the convex dielectric lens having a convex side oriented toward theincident light and a planar side oriented toward the photo sensitiveelement, wherein a bottom of the convex side of convex dielectric lensis level with a bottom surface of the second dielectric layer.
 8. Themethod of claim 7, further comprising: forming a dielectric structure onthe second dielectric layer, the convex dielectric lens and the grid,the dielectric structure at least partially covering the convexdielectric lens.
 9. The method of claim 8, wherein a refractive index ofthe convex dielectric lens is greater than a refractive index of thedielectric structure.
 10. The method of claim 8, further comprising:forming a color filter on the dielectric structure; and forming amicro-lens on the color filter.
 11. The method of claim 7, wherein theconvex dielectric lens is formed at least partially in the recess. 12.The method of claim 7, further comprising forming a pixel circuit on thefirst side of the substrate for electrical interconnecting with thephoto sensitive element.
 13. The method of claim 7, wherein a refractiveindex of the convex dielectric lens is smaller than the refractive indexof the second dielectric layer.
 14. A backside illuminated (BSI) imagesensor device, comprising: a substrate having a first side and a secondside opposite to the first side; a plurality of photo sensitive elementson the first side of the substrate to receive incident light transmittedthrough the substrate, wherein the photo sensitive elements arerespectively in a plurality of pixel regions of the BSI image sensor; afirst dielectric layer disposed on the second side of the substrate; asecond dielectric layer directly on the first dielectric layer, whereina refractive index of the first dielectric layer is greater than arefractive index of the second dielectric layer; a grid on the seconddielectric layer; and a plurality of convex dielectric lenses on thefirst dielectric layer and respectively within the second dielectriclayer, wherein each of the convex dielectric lenses has a convex sideoriented toward the incident light and a planar side oriented toward thephoto sensitive element, and a distal end of each of the convexdielectric lenses is in a position lower than a top surface of thesecond dielectric layer; wherein a bottom of the convex side of each ofthe convex dielectric lenses is level with a bottom surface of thesecond dielectric layer; and wherein a refractive index of the convexdielectric lenses is smaller than a refractive index of the seconddielectric layer.
 15. The BSI image sensor device of claim 14, furthercomprising: a dielectric structure on the second dielectric layer, theconvex dielectric lenses and the grid, the dielectric structure at leastpartially covering the convex dielectric lenses.
 16. The BSI imagesensor device of claim 15, wherein a refractive index of each of theconvex dielectric lenses is greater than a refractive index of thedielectric structure.
 17. The BSI image sensor device of claim 14,wherein each of the convex dielectric lenses is sandwiched by oppositesides of the second dielectric layer and the grid.
 18. The BSI imagesensor device of claim 14, further comprising: a plurality of pixelcircuits on the first side of the substrate for respectively electricalinterconnecting with the photo sensitive elements.
 19. The BSI imagesensor device of claim 15, further comprising a color filter on thedielectric structure.
 20. The BSI image sensor device of claim 19,further comprising a micro-lens on the color filter.